Impact wrench



June 17, 1952 c. E. FITCH 2,600,495

` IMPACT WRENCH Filed oct. 27, 1948 f l 2 SHEETS- Smm 1 June 17, 1952 c. E. FITCH 2,600,4'95

IMPACT WRENCH Filed OCb. 27, 1948 2 SHEETS-SHEET 2 Patented June 17, 1952 UNITED srArs 1 13 Claims. 1

This invention relates to an impact tool and more particularly to a clutch arangement for an impact tool by means of which a succession of rotational hammer blows may be imparted through an anvil to a driven member such as a nut, bolt, screw or the like which offers resistance to rotation during a tightening or loosening operation.

It is an object of the invention to provide such a tool wherein breakage of parts during normal use is reduced to a minimum. Devices of this sort in the past have required frequent replacements of broken parts and this results in high' maintenance expense and loss of time. The inherent Weaknesses in the tool have always been a limiting factor with regard to the amount of impact force available. This present device is not only economical from the standpoint of maintenance but is a more eiective impact tool in that it permits greater impact force to be made available.

The foregoing constitute some of the principal objects and advantages oi the present invention, others of which will become apparent from the following description and the drawings, in which Fig. 1 is a longitudinal sectional view through the impact mechanism forming the subject matter of the present invention, showing the same attached to a motor that is illustrated in elevation;

Fig. 2 is a transverse sectional view through the impact mechanism, the view being taken on the line 2-2 of Fig. 1 and illustrating the hammer locks in a neutral position;

Fig. 3 is a view corresponding to Fig. 2 but illustrating the hammer locks in striking position;

Fig. 4 is a view corresponding to Fig. 2 but illustrating the hammer locks in reset position prior to application of the striking force;

Fig. 5 is a longitudinal sectional view through the impact mechanism, the View being taken on the line 5 5 of Fig. 1;

Fig. 6 is a transverse sectional view through the impact mechanism. the view being taken on the line 6-6 of Fig. 5; and

Fig. 7 is a transverse sectional view of the impact mechanism, the view being taken on the line 'l-'l of Fig. 5.

For purposes of illustration a single embodiment of the invention is shown in the drawings and will be described hereinafter. It is recognized, of course, that many modifications may occur to the man skilled in the art A and it is intended that such modifications may be made in the embodiment shown without departing from the intended scope and spirit of the invention.

Referring now to the drawings the present invention is illustrated in the form of an impact tool generally illustrated at l5 that includes a motor portion I6 which for purposes of illustration may be a compressed air motor. The invention is not limited to this type of motor. however, as an electric motor as well as other types will serve equally well. The motor I6 as shown is provided with a flange portion I1 to which is attached by means of screws I8 a housing i9. 'Ihis housing I9 includes a clutch assembly generally indicated at 2D.

The details of the motor I6 are unimportant insofar as concerns the present invention inasmuch as they form no part of the invention For present purposes it is necessary merely to disclose a motor shaft 2l that is driven by the motor and is splined as at 22 to an upper plate or cage member 23 that is contained in the housing I9. This upper plate or cage member 23 is disposed in the upper region of the housing I9 and is bolted by means of bolts 24 to a lower plate or clutch member 25.

Mounted between the upper and lower plate or cage members 23 and 25 is an anvil 26 that is provided with a downwardly projecting shank portion 21 that projects through an aperture 28 in the lower plate 25. This shank 21 of the anvil 25 projects through an aperture 2B provided in the lower face of the housing I9, and to the lowermost end of the shank 21 as at 30 may be attached a screw driver, socket or other type of tool to which the impact is to be applied.

Also mounted between the upper and lower plates 23 and 25 is a pair of roller locks 3|, each of which is pivotally mounted on one or the other oi' the bolts 24 so that each of the roller locks 3| can rock back and forth about its respective bolt 24. When the two roller locks 3l are in their positions shown in Fig. 2 they form in effect substantially a complete circular unit with their abutting ends spaced only a very small distance apart. Both the upper and the lower plates 23 and 25 are provided with a pair of oppositely disposed radial grooves 32, the grooves in the upper plate 23 being aligned with the grooves in the lower plate 25. A pair of impact rollers 33 extend vertically between the upper and lower plates 23 and 25 and project at their opposite ends into the radial grooves 32 in the upper and lower plates 23 and 25 respectively;

These rollers 33 are adapted to ride in the grooves 32 radially with respect to the plates 23 and 25.

As shown in Fig. 2 each of the roller locks Si is arcuate in shape and is provided adjacent to each `of its ends on its inner face with an outer arcuate seat portion 3ft and an inner arcuate seat portion 35. The inner face of each roller lock 3l throughout the major portion of its length is substantially circular as at 36 but is provided with a cam projection; 31 located on one side of the adjacent bolt 24 forming the pivot for the roller lock and a second cam projection 38 located on the other side of the bolt 24. The anvil- 26 is substantially completely surrounded by; the cooperating roller locks 3i and when the hammer locks are in the position shown in Fig. 2 theyv are disposed concentrically about; the;v anvil 2123...

The anvil 26 is substantially cylindrical inform but is provided with a pair of oppositely-l disposed radially extending lobes 39. As shown in Fig. 5 the shaft 2|. of the. motor isbored atll andthe lippenV part of;` the anviL 26 is; bored as` at'. 4l to. receive a. centering'pinj 42' that; centers-v or guides the anvil with respect to the upper plate, 2 3. Each. impact rollerl 3.3; is, held between` the` outer arcuate seat, portion 3,4 of the adjacent. roller locks4 35|.' andthe adjacentlobev 3.9'- of thev anvil` 25 andunder these conditions the complete assembly. including the roller locksp3l, the bolts 24; and the. upper and lowerfplates, 23 and 25 are freeto-y move. as. a unit aboutthe` anvil 26, carryingr with themy the. impact'rollers, 33 that move over the arcuate, outerv surfacesof the, lobes 38 of the ari-villa InFi'g.` 3 the;l i-:flements` are; shown inA theii` posi,-V tion for driving.: the anvil` 2,6( directly from the driven shaftA 2lof;` the motor., InY the; position shown in-L Eig; eine elements aregshowrrin an, inr termediate `position where the; anvil. 26, is;` stationary4V and thefrollerflocks; 3| are, being rotated. at. a. relatively high velocity along Wit-.nth :upper: lower pla-tes 25.-. and 2.55 respeotivelvpriorto the annliloationof; the. impact, that; takosxplaoe at. the: time. the elementsv assume the position shownin Eig.. 3;

For purposes of explaining the: operation o f the present device let it beasswnfd: thatasocket of ther norma-1e socket; wrench, type; is; secured tov the lower-2116i o f; theshank 2-1'o f the anvil 23. It will be: assumed that theoperation` to be performed is.'the-tiglfitgening of a nut on a( bolt.. The socket is; iirst applied` over the nut and the tighteningA operation commenced. Shaft .2i is rotated by themotor I6 and under these conditions` the parts willaloeA disposed in the positionv shoivnvin Fig. 3.

The; drive from Shaft 2|- s. effected through upper: pla-teI 23; (Fig, 1) through; bolts 241,f lower plate; 25,l through the-roller looks 3i, impact rollers 33, and iinaly to the,4 anvil 26. Thus the motor I5- is connected to the, mutano; rotates the` nut toward, itsV tightening condition, When the-v nut rst rea-chesitsinitial tightened condition a resistance to turning is; imparted to the anvil 2.6. This causes then anvil, 2li`v to force, the impact rollers 33, outwardly.v in their respective grooves- 3-2. until. theA rollersliI climb` over-the corresponde ing lobes 3:9, onA the. anvil 26;. When, this occurs the elements, are in the: position shown in Fig, 2, so; that, the; anvil 26. isl nowf allowed to remain at rest While thej remaining elementsmaking up the prior to the application of the impact that follows. The roller locks 3| with their remaining assembly continue to rotate about the stationary anvil 26 until the cam projections 38 reach the respective lobes 3S of the stationary anvil 26 at which time roller locks 3l are caused to rock in the opposite direction at a high rate of speed to the position sho-wn in Fig, 3 where the roller locks 3| engage the impact rollers 33 to force thefigollersinto their innermosirpositionsjn their respective groovesv 32 andthen the entire kinetic energy of the moving cage including th-e upper and lower plates 23 and 25 together with the roller; Locks 3l on their pins or bolts 24 is given up in the form of an impact force against the lobes-3S of the anvil 26. This force is exerted front platos: 2.3,.. and 25 through the sidesof grooves andthe rollers 33 onto the anvil lobes 26: The roller locks in their positions shown in Fig. 3 hold rollers 33 in position to strike anvil lobes.- 'If'hsimnaotioroo impacts. anadditional' tighteningfoloe.- ontothe mit; following; which theoperatiQn .is repeated.

Thev reverse shock subjected by thea-nvil; 25.- against, the impact.. rollers, 33;, isA transmittodr ybyY the rollers; 33 in most part, to.. the, edges ot the grooves 3,2. of upper and lower platesc 23, and. 25, Only a very small portion of this reverse shock; is transmittedI through the roller locks 3.1E so that neither theiroller locks. 3:1- nor. the bolts Z4 aresubjected to heavy, shock, loading. during` normaloporation. of-l the present, device.. Tbisnionnesents a distinct advantage over prior. `devions. of; this nature because vthe roller looks. and thi-:air` ree. speenvec bolts 2a are." relatively f ragileas corps-. pared with. theriunperand lower plates 23.- and;V 25. and.. thus the bteakasais tattooed! to a. minimum It. is tobenotedfthat nvilvf.. tis-.shownin Fiss. 2 toi.- inolusive is. symmetrical about tsiver. tical axes Each of the toller looliSfGI-i is. sinn-- inetrical about its transverse axis passing through. the centen of Ibolt 24, Thu-s the-deviceavill'operate when thev` motor shatt. Zh is rotated inA either clockwise or counteiiclockwisediigection.

I claim:

1. An impact mechanism comprising arotary anvil, astriking lobe, onv the anyiL. arota-ry. impact member, rotatable, independently of. the. anvil, an intermediate.member-movable between@ the impactmembenandati-1e anvil` lobe for trans` mitting the impact load from the impact mem-1 ber to theanyillobe, andlocl; means carried-.- by the impact member.- and opelated-l by the anvily for positivelymoving;thenterrnediatemembor.

2. An impact mechanism comprising, a rotary1 anvil, a striking; lobeon. theanvil and an impact assembly mounted concentrically-aboutthe anvilf and rotatable independently of the anvil, the assemblv comprisingZ spaced upper. andlovvorv plato members, loohmoansibetwoentliaplate members pivot means. mounting theflook: means. on the plate members; so, that. the loch. means. canrocl: about said pivot. means, and intetmediate member engageable by the relierk loch meansto be maintained in position to; engage the anvil lobe, for transmittingA the impact. load;` fromA the` impact assembly to theanvil lob.;t11!.l0ok means beine: adopted.: to. rook. from a. position Wherert Y ene-.ases thoiintermediatemeans,toimaintan the latter in the path of the anvil lobeto a with.- drawniposition.

3. An. impact mechanism, oonmrisins; a. rotary anvil. a strikine lobeon tho:- anvil, and an; impactassembly mounted: conoenttioally about. the anvil andi rotatable independently of tha anvil,5 the as-,

sembly comprising spaced upper and lower plate members, lock means between the plate members, pivot means mounting the lock means on the plate members so that the lock means can rock about said pivot means, and van intermediate member mounted to slide radially between the upper and lower plates and adapted in one position to engage the anvil lobe, the lock means being adapted to rock from a position where it engages the intermediate means to maintain the latter in the path of the anvil lobe to a withdrawn position.

4. An impact mechanism comprising a rotary anvil, a striking lobe on the anvil and an impact assembly mounted concentrically about the anvil and rotatable independently of the anvil, the assembly comprising spaced upper and lower plate members, lock means between the plate members, pivot means mounting the lock means on the plate members so that the lock means can rock about said pivot means, a radial groove in each of the upper and lower plates, an intermediate member, the intermediate member projecting into the grooves, the intermediate member being adapted to slide in the grooves and in one position to lie in the path of the anvil lobe while at the same time being engageable by the lock means, the lock means being adapted to rock from a position where it maintains the intermediate means in the path of the anvil lobe to a withdrawn position.

5. An impact mechanism comprising a rotary anvil, a striking lobe on the anvil and an impact assembly mounted concentrically about the anvil and rotatable independently of the anvil, the assembly comprising spaced upper and lower plate members, lock means between the plate members, pivot means mounting the lock means on the plate members so that the lock means can rock about said pivot means, a radial groove in each of the upper and lower plates, an intermediate member, the intermediate member projecting into the grooves, the intermediate member being adapted to slide in the grooves and in one position to lie in the path of the anvil lobe while at the same time being engageable by the lock means, the lock means being adapted to rock from a position where it maintains the intermediate means in the path of the anvil lobe so as to exert a striking force against the lobe to a withdrawn position, the direction of the striking force against the anvil lobe being transverse with respect to the grooves.

6. An impact mechanism comprising a rotary anvil, a striking lobe on the anvil and an impact assembly mounted concentrically about the anvil and rotatable independently of the anvil, the assembly comprising spaced upper and lower plate members, roller lock means between the plate members, .pivot means mounting the roller lock means on the plate members so that the roller lock means can rock about said pivot means, and an elongated roller extending between the upper and lower plates and fixed to rotate with the plates, the roller lock means being adapted to engage the roller, the roller being adapted to engage the anvil lobe for transmitting an impact load from the impact' assembly to the anvil lobe, the roller lock means being adapted to rock from its position where it engages the roller when the latter is in engagement with the anvil lobe to a withdrawn position to permit the roller to clear the anvil lobe.

'7. An impact mechanism comprising a rotary anvil having a striking portion, and a rotary impact assembly comprising an upper and a lower plate sandwiching the anvil therebetween, a pair of substantially semi-circular'roller locks sandwiched between the plates and mounted to form together substantially a circle, pivot means disposed substantially in the center of each semicircular roller lock securing the roller locks to the upper and lower plates but permitting rocking of each roller lock about its pivot from an impact position to a neutral position, an intermediate impact roller disposed between the abutting ends of the roller locks and the anvil and adapted to clear the anvil striking portion when vthe roller locks are disposed in neutral position, and cam means on each roller lock adapted to engage the anvil to rock the roller lock from neutral position to impact position, the intermediate impact roller being adapted to strike the anvil striking portion and concurrently being disposed in engagement with the roller lock when the latter is disposed in its impact position.

8. An impact mechanism comprising a rotary anvil having a striking portion, and a rotary impact assembly comprising an upper and a lower plate sandwiching the anvil therebetween, a pair of substantially semi-circular roller locks sandwiched between the plates and mounted to form together substantially a circle, pivot means disposed substantially in the center of each semicircular roller lock securing the roller locks to the upper and lower plates but permitting rocking of each roller lock about its pivot from an impact position to a neutral position, an intermediate impact roller fixed to rotate with the upper and lower plates and mounted to move radially on the plates, the intermediate impact roller being disposed between the abutting ends of the roller locks and the anvil and adapted to clear the anvil striking portion when the roller locks are disposed in neutral position, and cam means on each roller lock adapted to engage the anvil to rock the roller lock from neutral position to impact position, the .intermediate impact roller being adapted to strike the anvil striking portion and concurrently being disposed in engagement with the roller lock `when the latter is disposed in its impact position.

9. An impact mechanism comprising a rotary anvil, an impact hammer member, an impact roller between said anvil and impact hammer member, a locking member actuated -by said anvil positively to move the impact roller into locking position at a predetermined position.

10. An impact mechanism comprising a rotary anvil, a striking lobe on the anvil, an impact assembly mounted concentrically about the anvil and rotatable independently of the anvil, impact transmitting means between the anvil and the impact assembly, and means actuated by the anvil positively to move the impact transmitting means into the path of the anvil lobe.

ll. An impact mechanism comprising a rotary anvil, a striking lobe on the anvil, an impact assembly mounted concentrically about the anvil and rotatable independently on the anvil, impact transmitting means between the anvil and the impact assembly, and means controlled 'by the anvil for positively moving the impact transmitting means into impact position at a predetermined position of the impact assembly with respect to the anvil.

12. An impact mechanism comprising a rotary anvil, a striking lobe on the anvil, an impact assembly mounted concentrically about the anvil and rotatable independently of the anvil, impact Gex-Lie@ by' the imnee; and:

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